Refactor desired retention logic to use a dedicated method for improved clarity and maintainability.

rslib/src/decks/mod.rs

@@ -31,6 +31,7 @@ pub(crate) use name::immediate_parent_name;
 pub use name::NativeDeckName;
 pub use schema11::DeckSchema11;
 
+use crate::deckconfig::DeckConfig;
 use crate::define_newtype;
 use crate::error::FilteredDeckError;
 use crate::markdown::render_markdown;
@@ -89,6 +90,16 @@ impl Deck {
         }
     }
 
+    /// Get the effective desired retention value for a deck.
+    /// Returns deck-specific desired retention if available, otherwise falls
+    /// back to config default.
+    pub fn effective_desired_retention(&self, config: &DeckConfig) -> f32 {
+        self.normal()
+            .ok()
+            .and_then(|d| d.desired_retention)
+            .unwrap_or(config.inner.desired_retention)
+    }
+
     // used by tests at the moment
 
     #[allow(dead_code)]

rslib/src/scheduler/answering/mod.rs

@@ -445,14 +445,7 @@ impl Collection {
             .or_not_found(card.deck_id)?;
         let config = self.home_deck_config(deck.config_id(), card.original_deck_id)?;
 
-        // Get deck-specific desired retention if available, otherwise use config
+        let desired_retention = deck.effective_desired_retention(&config);
-        // default
-        let desired_retention = deck
-            .normal()
-            .ok()
-            .and_then(|d| d.desired_retention)
-            .unwrap_or(config.inner.desired_retention);
-
         let fsrs_enabled = self.get_config_bool(BoolKey::Fsrs);
         let fsrs_next_states = if fsrs_enabled {
             let params = config.fsrs_params();

rslib/src/scheduler/fsrs/memory_state.rs

@@ -215,11 +215,7 @@ impl Collection {
 
         // Get deck-specific desired retention if available, otherwise use config
         // default
-        let desired_retention = deck
+        let desired_retention = deck.effective_desired_retention(&config);
-            .normal()
-            .ok()
-            .and_then(|d| d.desired_retention)
-            .unwrap_or(config.inner.desired_retention);
 
         let historical_retention = config.inner.historical_retention;
         let params = config.fsrs_params();